A head-up display or HUD is a transparent display panel that presents information to a user without requiring users to look away from a preferred viewing direction. The origin of the name stems from a pilot being able to view information with the head positioned “up” and looking forward, instead of angled down looking at lower instruments. Although they were initially developed for military aviation, HUD systems are nowadays used in commercial aircraft, automobiles, and other applications.
For example a driver can view traffic and the road in front of the vehicle through the transparent panel of a HUD system that is attached to a dashboard close to a windshield of the vehicle. A typical HUD system comprises a combiner, a projector and a video data source such as a computer. The combiner is typically an angled flat piece of glass or plastic located directly in front of the viewer that redirects the projected image from the HUD projector in such a way as to see and therefore combine the field of view and the projected image at the same time. Combiners may have special coatings that reflect the monochromatic light projected onto it from the projector unit while allowing all other wavelengths of light to pass through. In some optical layouts combiners may also have a curved surface to refocus the image from the projector. A combiner is comparable to a semi-transparent mirror. The HUD projector is usually mounted above or below the combiner. The computer provides the interface between the HUD projector and the systems or data to be displayed and generates the imagery and symbology to be displayed by the HUD projector towards the combiner which then further projects the images to the user.
Combiner positioning mechanisms for a HUD system which can be moved between a storage position and an operating position are known in the art. For example such a combiner is disclosed in document WO 2013/004611 A1. In this known design the combiner is stored in a housing when in a storage position and protected by a cover in its closed position. A drive mechanism of the HUD moves the combiner around a combiner axis from the storage position to the operating position to project out of the vehicle's dashboard. A planetary gearing is used to at the same time turn and slide the cover from its open position into its closed position. The housing of this known HUD system comprises a substantial volume as the cover in its open position elongates the combiner in its operating position into the housing. This makes it difficult to design this HUD system into a dashboard as a lot of other devices have to be fed into it as well and volume available for the housing of the HUD is restricted.
The document U.S. Pat. No. 8,619,369 B2 discloses a HUD system with a combiner linear movable in a direction perpendicular to the surface of the dashboard from its storage position into its operating position and with a cover pivoted around a cover axis to move the cover from its closed position to its open position. The housing of this known HUD system reaches quite deep into the dashboard what makes it difficult to design this HUD system into a dashboard.
The aim of the invention is to provide a HUD system that overcomes the disadvantages of the HUD systems known in the art. This problem is solved by a head-up display system with a cover according to the preamble of claim 1 with the features of the characterizing part of claim 1. The subjects of the dependent claims concern further advantageous embodiments of the invention.